Reliable Data Transfer: Go-back-n
Learn how the Go-back-n protocol uses a sliding window and cumulative acknowledgments to detect lost packets and manage retransmissions. Understand its operation, advantages, and limitations in reliable data transfer compared to selective repeat.
In the last lesson, we discovered that a sending sliding window alone is not enough to ensure detection and retransmission of lost packets. In order to do that, we will look at two protocols:
- Go-back-n
- Selective Repeat
Go-back-n
The simplest sliding window protocol uses go-back-n recovery.
Go-back-n Receiver
Intuitively, go-back-n receiver operates as follows:
- It only accepts the segments that arrive in-sequence.
- It discards any out-of-sequence segment that it receives.
- When it receives a data segment, it always returns an acknowledgment containing the sequence number of the last in-sequence segment that it has received.
Cumulative Acknowledgements
This acknowledgment is said to be cumulative. When a go-back-receiver sends an acknowledgment for sequence number ...